Commando caliper dismantle

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Well I had success with getting the inboard piston to move on both of the calipers from my Mklll. I lucked out and found an aluminum plug in a box of random fittings that threaded into the supply port. I drilled and tapped it for a standard grease nipple. Then used a couple of aluminum plates clamped over the outer piston to hold it in place, liked mentioned earlier. Connected a grease gun and proceeded to fill it up with grease. Once volume maxed out, pressure began to build and the inner piston moved out of its bore before the seal gave way and grease oozed out. Worked well on both. Now I get to tackle the big outside threaded plug to gain access for removing the outer piston. Also need to free the bleeder port nipple, so I will probably try the above "boiling it in the old saucepan of plain water" trick to loosen each of them before wrenching on 'em. Cj
 
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Plug is steel, caliper alloy so heating will expand the alloy more as long as its fully heat soaked. A localised heat of the alloy is counterproductive, the outer cool bit will cause the expansion to be inwards against the steel plug not outwards.
 

batrider

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Would recommend using a proper brake bleeder wrench on the bleeder. These are much thicker than a normal wrench and they are long so you can apply more force safely. Heat would be good on the caliper around the bleed nipple if really stuck.
Russ
 

Time Warp

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On the stock caliper I just put it in the machine vice in the mill with plastic bread board to protect it.
Fit the Norvil tool into the pin recesses then with a scrap of alloy on top of the tool bring the quill down and lock it.

The tool can not lift so the pins can not come out and loosening and retightening is easy with no drama.
I put a little lubricant on the plug contact faces so if I ever have to do it again it will be the same.
 

Time Warp

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Now rebuilt calipers,,,,,,, wonderful...
Now to install and bleed them. That's when the fun starts. I occasionally get call by professional shops for tech advice.
In this case, one email asked about difficult and air bleed reluctant calipers. This difficulty is quite common.

Referencing my pix in post 1 this was my suggestion:

"The problem/solution is I guess about bubble control. The pix shows the rear piston can get vented at the rear top to the bleeder and the front/outer can vent through the MC hose.

The inter-piston drilling is the extreme difficulty to overcome. neither bleeder nor MC hose motivates bubbles to move between sides.

Laying/holding the caliper horizontal with the rear piston down and angling bleeder partially up and pumping and releasing may move the bubbles up eventually to finally exit up to the outer piston and toward the hose. Holding lever with rubber band will help under pressure grain of sand bubble to finally rise to MC"

Normal bleeding is often helped with the overnight rubber band hold under pressure on the brake lever. This turns a big bubble to the size of a grain of sand.

Pre filling and bleeding with a combination simultaneous dual hose port and bleeder port fixture may be of very significant value.
 
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